Brewing



Feb. 24, 1942. A M FISCHER 2,273,853

BREWING Filed Oct. 22, 1937 3 Sheets-Sheet l ATTORNEYS Feb. 24, 1942. A.M. FISCHER BREWING Filed ct. 22, 1957 3 sheets-sheet 2 ATTORNEYS Feb.24, 1942. A, M FlscHER 2,273,853

BREWING Filed Oct. 22, 1937 5 Sheets-Sheet 5 INVENTOR ATTORNEYS ,Ypackaged for use.

Patented Fb` .i24, i942 T OFFICE BREWING ApplicationvOctober 22, 1937,Serial No. 170,485

' (ci. ca -31) 33 Claims.

This invention relates particularly to the art of brewing beer, and hasfor an object the pro- :vision of an improved brewing process and systemwhereby, among other advantages, an improved beer product having bettertaste and aroma, better keeping qualities, and al higher nutritive valuethan'- the beers'heretofore available Amay be produced. 'The inventionis particularly directed to l the provision of a vitamin beer,especially one to which the original yeast vitamins have been restored.1 ,A

Although the'invention is particularly directed to the brewing of beer,certain features have somewhat broader application. Thus, the yeastextract produced in accordance with this process,

- beer has often been called liquid bread." In

former"years this was indeed an appropriate name, but, unfortunately, atthe present time itis not so truly the case. y j

In former vyears it was not customary to filter the beer as sharply asat the present time'. Consequently yeast cells were left in the finishedbeer,

thus contributing their vitaminand enzymic con# tent to the otherwisepurely caloric content of fthei beer.

Thus the finished beer was a'wellbalanced nutritious beverage,possessing both ,-...caloric and vitamin content. Y .'iHowever,in'modern brewing practice, particularl-.yrin'y the American type ofPilsener beer, it is :considered highly desirable to obtain a clear,'brilliantf'product. To obtain such a product, it is customary tosubject the beer to very sharp filtration. before the beer is bottled or otherwise In this final iiltration all the yeast cells are removed.

It has been established that although large quantities of vitamins arepresent in the beer during the brewing process, coming from both the`wort and the pitching yeast, these vitamins are absorbed to a largeextent, if not entirely, by the yeast during the fermenting operation.These able factors such as enzymes, mineral salts. lecithin, etc., whichare also removed in the final filtration. The great nutritional andtherapeutical value of these substances is recognized and accepted byscientists, yet the brewing methods customarily employed do not securetheir incorporation into the finished product to an appreciable extent.

It is an object of the present invention to restore these yeast vitaminsand enzymes, which were formerly present inthe finished beer, to beersof themodern Ybrilliant type. The incorporation of vitamins in beer isrendereddimcult by the highly sensitive nature of the beverage. Anychange in the brewing process, andparticularly the addition of anyforeign substances, are carefully scrutinized by the brewmaster. It is,therefore, important not to impair the ordinary `characteristics of thebeer, such as taste,bril

llancy, aroma, foam, stability, etc., in vitaminizing the beer.

`A number of methods for incorporating vita- 4mins into finished beerhave heretofore been suggested. Among these methods might be mentionedthe'addition of autolyzed yeast to the beer,

,with or without subsequent irradiation of the beer by ultra-violetrays. In the processes employing been found to adversely affect itstaste. perhaps due to the chemical changes which take" autolyzed yeast,the yeast cells are completely ,destroyed by autolysis and `theentirecell content released. This'is customarily accomplished byprolongedheating of the yeast cells. This `process has not been foundsatisfactory since the addition of autolyzed yeast to the beer has Thisis place during the autolysis process.

In the usual method of brewing, yeast is added to the wort for the firstor main fermentation,

vitamins are apparently not released byhealthy yeast cells under normalbrewing conditions and are, of course,` removed with the yeast cellsduring which lasts normally for a period of from 7 to 10 days. Duringthis period the yeast propagates itself and normally increases from 3 to5 times in volume. pleted most of the yeast is removed, and the beveragethen undergoes a second or after fermentation, during the lager period,which is comparatively gentlev and mild and for the purpose of improvingthe taste and aroma of the beer. In cases where the Krausen method isemployed, a quantity 'of yeast from the main fermentation stage is addedduring this lager period in order to saturate the beer with natural CO2.`When this aging or lager period is completed, the yeast still insuspension in the beer is removed by sharp the final filtration. Yeastcontains other valu- 55 filtration in order to obtain asparkling andstable After the main fermentation is combeer, and the beer bottled orotherwise packaged for consumption.

In accordance with the present invention, a quantity of yeast is agedwith a suitable solute or solutes. for example, common salt and canesugar. and the mixture passed through a suitably constructed colloidmill, the conditions being so controlled that a portion of the yeastcell content is extracted without the disruption of the yeast cellmembranes. Thus, the yeast cell wall is employed as a filter, and onlythose portions of the cell content which can pass through the cell wallis extracted. In this manner an extract of pleasant flavor may obtained,free of yeastcells and free of those portions of the cell contents whichare not permeable through the cell membranes. The extract so obtained.with or without ultra-violet irradiation, is added to the beerl at thedesired point in the brewing operation.'

detail:

Yeast employed The yeast employed is .preferably brewers yeast obtainedfrom the surplus yeast produced during the fermentation of the beer,since large quantities of yeast are produced in this manner and arecustomarily discarded as a waste product. It is well-known that brewersyeast is an exceedingly rich natural source of vitamins B and G-complex,

and also contains other desirable nutritional factors. If desired,however, brewers pure culture yeast, or other suitable yeast, may beemployed.

If surplus brewers yeast is employed, preferably the middle layer of theyeast sediment from the fermenting tank is employed, as it contains aminimum of impurities. 'I'his yeast is sieved so as to remove hopresidues and other impurities of larger magnitude. If desired, it may bewashed, although this has been found unnecessary in most cases. s

solutes To yeast so prepared, an extractive agent is added. I prefer touse a mixture of common salt (sodium chloride) and cane sugar. These.

solutes are solublein beer or water and, when added to the yeast, beginthe extraction of the cell contents by plasmolytic action.

Ii' desired, other suitable solutes may be employed. In selecting thesolute, characteristics such as non-toxicity, non-deleterious effect onthe beer characteristics, capability of inducing plasmolysis, etc.,should be kept in mind. Among the edible solutes which may be employedwith more or less success are: sugars, such as sucrose,

sugar syrups and molasses, malt extract, saccharines, gum arabic, sodiumchloride, and potassium chloride.

These substances are known as plasmolyzing agents, that is, they havethe property of extracting from the yeast-cellsl at least a portion ofthe yeast-'cell contents, including uid and soluble constituentsthereof.

'I'he proportions of the solutes whichy may be employed may vary widely,and should be selected in accordance with the other conditions of thebrewing process. In the case of vcommon salt and cane sugar I have foundit advisable to employ a relatively small quantity of salt, ranging from'about to 2%, by weight, based on brewers yeast of fairly thickconsistency. Con- .glucose and maltose, sugar preparations, such as 20ADescribing' the process of the invention in more K ployed, but it isadvisable not to use too much salt in order to avoid possible impairmentof the foam retaining quality of the beer, amongst other things. This,of course,will depend, amongst other considerations, upon how much ofthe extract is added to a given quantity of beer. When adding theextract from 25 to 50 gallons of brewers yeast to 100 barrels of beer, Iprefer at the present time to employ about l/2% of salt, by weight,based on the quantity of brewers yeast.

As to the amount of cane sugar which may be employed', I prefer toemploy a considerably larger amount of sugar than of salt. Theproportion of sugar may also vary widely, and is determined, among otherfactors, by the character of the beer and the amount of extract added toit. Proportions ranging from about 4% to 25%, by weight, Abased onbrewers yeast of fairly thick consistency have been employed withsuccess. Indeed, the proportion may be considerably higher than this ifonly a small amount of extract is added to the beer. Good results havebeen obtained with 15% of sugar when adding the extract obtained fromabout 25 gallons of yeast to 100 barrels of beer.

Aging and colloid mill treatment 'I'he length of time and thetemperature at which the yeast is aged with the solute or solutes, forexample, with common salt and cane sugar, may also vary considerably.Generally speaking, I may adopt either of two procedures, depending uponwhich is more suited to the conditions of the particular brewery inwhich the process is emp oyed.

In one of theseprocedures the temperature and duration of the agingperiod, the length of time and temperature of the treatment in thecolloid mill, and the conditions under which the treated yeast issuingfrom the colloid mill is kept and used, are so controlled that the yeastcells are not killed or their qualities otherwise impaired. Toaccomplish this the entire processing of the yeast is carried on as atlow temperatures as possible, preferably close to zero (centigrade). Theaging period will preferably last for from 15 minutes to several hoursat a low temperature, although, if desired, it may be extended for aperiod of several days. The period ofn aging should not, however, beextended tothe point where substantial autolysis occurs, therebycreating harmful substances. When aged for a period of several days,difiiculties are sometimes encountered due to the fact that even at verylow temperatures some fermentation occurs. To avoid this diiliculty, theyeast may be aged first with salt alone, and only a short aging periodemployed after the sugar has been added.`

At the end of the aging period the mixture is passed through a .colloidmill. Some brewers yeasts are sumciently liqueed by the amount of beerthey contain and plasmolysis so as to make further dilution unnecessary.If, however, the yeast is of high consistency, or if compressed yeast isused, further dilution is advisable to assure eilicient extraction inthe colloid mill. This dilution can be accomplished by the addition ofbeer or water.

In the colloid mill, due to a combination of hydraulic shearing action,centrifugal force of high magnitude and intensified plasmolysis,efilcient extraction ofthe yeast cell content takes place. The colloidmill is so designed and adsiderably higher percentages of salt may beemlusted that rupture of the yeast cells is avoided.

The colloid mill is preferably of the high speed smooth rotor type. Amill in which the rotor has a peripheral speed of `about 15,000 feet perminute and working gaps( of approximately 0.003 inch has been found togive good results. Somewhat higher speeds and smaller working gaps, forexample, 20,000 feet.y per minute and 0.002 inch, respectively, may beemployed if the construction of the machine permits.

During the course of treatment in the colloid mill the temperature ofthe yeast will ordinarily increase, unless special cooling means areemployed. It is, therefore, desirable to cool the yeast immediatelyafter it issues from the colloid mill. Ifdesired, a cooling system maybe built into the colloid mill. If the yeast is recirculated through themill, an exterior cooling system may be employed `with advantage.

When treated in this manner it is found that notonly are theyeast cellsnot destroyed, but they appear to be more highly activated than before.This is evidenced bythe fact that if the yeast is used to ferment a wortthe final yeast harvest for a given quantity of treated yeast is greaterthan for the same quantityof untreated yeast. If the treated yeast isnot immediately added to the beer, it is advisable to filter the yeastcells from the extract immediately, in order to avoid possiblereabsorptiony of the vitamins in the extract by the yeast cells.

j Since, during this procedure the yeast cells are not killed, autolysisof the yeast cells is avoided.

Thus there is no danger of the resulting extract being adverselyaffected byautolysis.

In many breweries, for practical reasons, Iit is undesirable to employthe above procedure in which the yeast cells remain alive, because ofthe constant attention necessary due to the fer; inenting activity ofthecells. In such vcases I employ a second procedure in which thefermentthe water naturally will be lowerd, so that the suspension isreheated to about 90 C. This reheating may require about 15 minutes. Bythis procedure-the fermenting power of the yeast is destroyed, but theperiod is not long enough for appreciable autolysis. The yeast is thenextracted in the colloid mill and cooled and filtered as previouslydescribed.

Another variation is to remove all fermentable substances from the yeastby washingv and pressing it, and then induce plasmolysis by adding asolute or solutes of the saccharine type, or a combination of a salt andsaccharine. After aging the mixture at a low temperature for asuitablelength of time, the suspension is further extractedfin a colloidmill. The advantage of this procedure is that there will besubstantially no fermentation during treatment even if room temperaturesare reached. The extract will then be separated by flltratiomasdescribed hereinbefore.

e Addition of eitract to beer The extract may be added to the beer atany time during the brewing procedure, depending upon the advantageswhich itis desired to secure. When the extract is made by the method inwhich the fermenting power of the yeast cells is not destroyed, bothyeast cells and extract` tion, the fermenting proceeds with greaterrapiding power of the yeastcells is destroyed, but the process iscarried out in such a wayA that autolysis of the yeast cells and ruptureof the yeast cell walls are avoided. In this procedure, I employ a shortaging period at a considerably higher temperature than employed in thefirst procedure above described, so as to kill the yeast cells and hencedestroy their fermenting' activity. The aging period, however, is madesulciently short so that no substantial autolysis takes place. For thisprocedure, aging for about 1/2 hourat about 70 C. is suitable.Considerably shorter times at this elevated temperature may be employed;for example, aging periods varyingA from 5 to 30 minutes may be employedwith more or less success. Also, temperatures above 70 C. may beemployed, if desired. I prefer, however, not to employ too long an agingperiod or too high temperatures in order to avoid adversely affectingthe vitamin potency.

. After passing the aged mixture through the colloid ymill itis thencooled down to a low temperature and the yeast cells filtered from theextract. It is preferable to do this as soon as possible after thecolloid mill treatment in order to prevent subsequent autolysis of theyeast cells from adversely aiIecting the extract.

ity 'than if untreated yeast were used, Aand tests indicate that ahigher degree of fermentation is obtained. In some cases, with untreatedyeast, the fermentation does not start readily. When treated yeast isused, this` difficulty is removed.

When the treated yeast is used for the main fermentation, the freevitamins in the extracted portion are absorbed .by the yeast cells kasthe fermenting proceeds, and again become unavailable for the finishedproduct. Therefore, I preferably add the treated yeast to the beertoward the end of the second' fermentation (or for both the main andsecond fermentations). When this is done, and the yeast cells areremoved in the nal filtering operation, tests indicate that the enzymesand vitamins remain in the beverage and are. therefore, available to theconsumer. Adding treated yeast during the second fermentation periodalso appears to quicken the aging and ripening of the beer, and tohasten the setafter fermentation, the finished beer will not.

contain all the vitamins which have been added, due to reabsorption bythe yeast cells. The amount of reabsorption will depend on the stage atwhich the extract is added. Therefore, if the primary consideration isthe addition of vitamins to the finished beer, and the above advantagesderived from adding treated yeast and extract for the main or afterfermentations are not thought sufiiciently important. the filteredextract may be added to the beer shortly before the final filtration, orpreferably, in order to avoid possible vitamin absorption in the beerfilter, to the finished beer. 'I'his procedure avoids any possiblereabsorption of the vitamins by yeast cells during the fermentation andlager It will be understood that in this speciiica'f periods. f course,extract may be added at each stage if desired, and treated living yeastused for both main and after fermentation, and in conjunction withuntreated yeast.

The filtration of the extract is preferably carried out in a so-calledplate and frame type filter press, employing canvas as a filter medium.The filtrate obtained from this press may be irradiated withultra-violet light so as to antirachicitically activate the extract,thereby producing vitamin D from the pro-vitamin D obtained from theyeast. This enables incorporating vitamin D, as well 'as vitamins B andG-complex in the beer. Irradiation may be employed before extracting ifdesired, but it is preferable to irradiate after' extraction in order toobtain greatest-eflioiency. Inorder to prevent the formation of ozoneduring irradiation, it is advantageous to provide an -atmosphere of anon-'deleterious gas, such as CO2.

'I'he filtrate obtained from the plate and frame filter press is usuallynot brilliant and stili contains colloidal turbidities and yeast cells.If the filtrate is added to the beer prior to the flnal filtration step,these turbidities and cells are ren.oved in the filtration. 'Ihis finalfiltration is normally carried out in so-called pulp filters.

There has recently been a tendency among brewers to employ kieselguhr(diatomaceous earth) filters in the nal filtration of the beer.Kieselguhr, while being an excellent filter medium, has the tendency toadsorb vitamin B, from the beer. In such a case it is preferable topreviously filter the extract to brilliancy and then add it to thefinished mtered beer. Even when pulp filters are used it may be.desirable to filter the extract to brilliancy before adding it to thebeer, the addition being either before or after the final filtration ofthe beer in the pulp filter. In filtering the extract to brilliancy, itis naturally desirable not to employ a filter medium which tends toabsorb the vitamins. `A filter employing slntered glass or wool has beenfound suitable.

Before adding the extract to the beer it may, if desired, be adjusted tothe pH of the beer, which is usually between 4.2 and 4.7. This may 'beaccomplished by adding a non-toxic acid such, for example, as lacticacid, tartaric acid, citric acid, acetic acid, etc. This adjustment ofthe pH value of the extract is particularly desirable when the extractis not used immediately, in order to avoid infection of the extract. ApH value close to 4 is found desirable to help prevent such infection.This feature is of some practical importance, since during the brewingseason it is desirable to have the vitamin extract made somewhat inadvance of use.

The pH might be adjusted at some other point in the yeast treatment ifdesired; for example, prior to passing the yeast through the colloidmill. The pH may be adjusted with advantage prior to any heat treatment,in order'to minimize destruction of vitamin B by the heat.

The amount of extract which is added to the beer is determined by theamount of vitamins which it is desired to incorporate in the beer.Excellent results have been obtained by the adn dition of the extractobtained from gallons of brewers yeast to 100 barrels of beer.Considerably larger amounts of the extract may be added to the beerwithout adversely affecting 'the taste and other characteristics of thebeer. An amount of extract corresponding to a ratio of about 50 gallonsof brewers yeast per 100 barrels of beer will give a very favorablevitamin/caloric ratio in the finished product.

Depending on the character of the beer, an amount of yeast extractnecessary to obtain a desired vitamin potency cannot always be addedwithout producing on'taste. This is especially the case with lighter,pale beers. In such a case I prefer to .concentrate the extract to suchan extent that small quantities sufce to give the beer the desiredvitamin content. For this concentration, I prefer to adjust the pH valueof brilliant filtered extract by the use of a non-toxic acid, asmentioned hereinbefore. The acidied extract is then concentrated in avacuum to a syrup consistency. During this concentration periodcaramelization of the sugars in the extract takes place, thus removingthe yeasty taste and producing a taste resembling that of malt or fruit.Higher acidity produces a more fruity taste. v The evaporation may beconducted under vacuum at temperatures of between 40 to 70 C. If duringthe concentration the pH of the extract should become too low it may beadjusted by adding a suitable alkaline material.

As an aid to the ready practice of the invention 'the following examplesare given, it being understood that the examples are intended asillustra--k tive only, and not as limiting the invention thereto.

` Example 1 To kilograms of sieved brewers surplus yeast are added lkilogram of sodium chloride and l5 kilograms of granulated cane sugar.The yeast, which due to the addition of the solutes immediately startsto plasmolize, is kept at a temperature close to zero (C.) and stirreduntil all of the sugar and salt have dissolved. The .suspension is thenpermitted to age for one hour at a temperature close to zero (CJ. Theyeast. which by this tirne has been entirely liquefied by plasmolysis,is now extracted in a colloid mill, avoiding a raise in temperature. Thetreated yeast suspension, after leaving the colloid mill, is collectedin a tank and kept at a temperature low enough to prevent substantialfermentation and autolysis, preferably close to zero. From there it ispassed through a lterpress having a canvas filter element, and theissuing filtrate collected. It is preferable to filter the suspension assoon as possible after the colloid mill treatment, so that the cells areremoved from the extract without delay. Acetic acid is then added toadjust the hydrogen ion concentration to about pH 4.2. The extract isthen given a final ltration in a illterpress having sintered glass, orwool','as a filter medium. lThis renders the extractcell-free andbrilliant. The so-treated extract is then added tov a small quantity ofbeer, where it readily dissolves, and the dissolved extract, containingthe vitamins B1 and G-complex and other valuable constituents, is addedto 100 barrels of finished filtered beer in such a way that uniformmixing with the beer is assured.

.Example 2 cilitate dissolving, the sugar may rst be dissolvedl in asufllcient quantity of warm water. The aged 15 mixture 1s then passedthrough a colloid mm'.

terasse The Imixture so treated, containing both yeast cells andextract, isv immediately added for the lager period 'to'beer' beingproduced by the Krausen process. yAbout threeparts of treated yeast areadded to one thousand parts of'beer, the basis being the brewer-'s yeastof fairly thick consistency. Yeasttreated in this way may also be addedto artificially carbonated beer at the be ginning of the lager period.

Example 3 f `To 100V `kilograms of sievedbrewers surplus yeast areeddedj soo grams er sodium chloride and 10" kilograms of granulated canesugar. The lyeast is' kept at atemperature close to zero (C.) andstirred until all the sugar and salt are dissolved. The suspension isthen permitted to age for about iOminutes at a temperature close tozero. The yeast, which by then has plas-l molized, is circulated in acolloid mill until the extract has acquired a' temperature of about 91'`C. The required time Awill vary with the capacity of the machine,but inone case was found to take abouttwenty minutes. In this case thefermenting power of the yeast cells is destroyed, due to the heat, butthey are not ruptured. The treated yeast suspension is collected in atank provided with a cooling system. There the extract is cooled down toabout 2 C. in about onehalf hour. From there it is passed through acanvas iilterpress and the issuing filtrate collected. 'I'his filtrationis preferably done as soon as possible after the extraction, tok avoidany possible autolysis of the yeast cells affecting the extract.. Anon-toxic acid, as for'instance acetic acid, is added to the iilteredextract so as to ad- Just the hydrogen ion concentration to about pH4.2. The rest of extract again and adding it to the beer isthe same asin Example l.

Example 4 The yeast is treated in exactly the same way as in Example 3,but instead of filtering the extract in the canvas filterpress onlyonce, it is recirculated through this filterpress until the extractbecomes fairly clear. The extract is then irradiated andsubsequentlyadded tothe lager tank in which the beer has undergone one preltration.The beer is subsequently filtered to brilliancy'in a pulp filter, the`filter preferably having a filter mass free of ypaper so as to avoid Yreabsorption of the vitamins.

Example 5 added slowly so thatthe temperature of the mix-V ture does notsink below about '15 C. As soon as the entire yeast is introduced thetemperature is raised to .about 90 C. and kept there for a few minutes.The yeast is then extracted in a colloid mill. .The further ytreatmentof the extract is identical with the treatment` described in Example?.

Example 6 the procedure of filtering the added to 30liters of slightlyacidied het water of about 95 C. in a steam heated kettle, the yeastbeing added slowlysothat the temperature of the mixture does not sinkbelow about 75C. 'Ihe water is acidied withl a non-toxic acid, forexample'. with acetic or'lactic acid. As soon as the entire yeastisintroduced, 30 kilograms of cane sugar syrup `(containing about 30%water) is introduced, and, under constant stirring of the mixture, thetemperature is raised to about 90 C. and kept there for a fewr minutes.'I'he yeast is then extracted in a colloid mill and the treated mixturecollected and cooled down to about 1 C. The further treatment or theextract is the same as described in Example 3.

Example 7 then passed into a receptacle and immediately cooled down toapproximately 2 C. As soon as the mixture is cooled, which may takeapprox-l imately one-half hour, or less, the mixture is filtered in acanvas iilterpress. Preferably, the extract is recirculated through thefilter press until a clear filtrate is obtained. The filtrate is thenadded to thek beer in the lager tanks at the end of the lager period,and shortly before the final filtration (which is carried out in pulpfilters) The filtrate from 25 gallons of brewers yeast is added Brewerssurplus yeast is first sieved and washed. kilograms of this yeast isthen to 100 barrels of beer. If the filtrate is not added immediately wme beer, the pH is adjusted to between 4.2 and 4.5 by the addition of asuitable quantity of lactic acid. Even when the filtrate is added to thebeer immediately, it is preferable to adjust the pH value in thismanner.

. If in the regular brewing procedure the beer is subjected to a slowartificial carbonation treatment for a period of a few days prior to thefinal filtration, the filtrate may be added to the beer at, thebeginning of this carbonation period.

Beer made as described in this example has been found to contain vatleast 8 International units ofvitamin B per 12 oz. bottle.

If so desired, in the examples just given, the extract may beconcentrated in the manner described hereinbefore. Also, ultra-violetirradiation may be employed.

When the process hereinbefore described is used it is found that a beerof high vitamin potency can be obtained without adversely affecting theother qualities of the beer, Indeed, in many cases improved color,taste. aroma and foamkeeping qualities are noted. Furthermore, althoughconsiderable yeast cell content is added to the beer no yeasty taste isnoticed. The treat ment has also been found to have positive value inpreventing deterioration of the taste of the beer when it ispasteurized. This is important since pasteurization usually impairs thetaste of beer brewed in the ordinary manner. The keeping qualities ofthe beer also have been found to be excellent. 1 L

In the practical carrying out of my process on a commercial scale, it isdesirable to employ a colloid mill which is so designed and constructedthat the treatment of large quantities of yeast may be carried outrapidly and efdciently in as short a time and with as little attentionas possible. 'Ihe colloid mill illustrated in Figs. l to 6 has beendesigned to meet these requirements. It will be understood that it isnot necessary to employ a colloid mill of this construction in thecarrying out of my process, but that any other suitable construction maybe employed if desired.

In the drawings:

Figure 1 is a vertical section of the colloid mill taken along the axisof the machine, one irotor being shown in full:

Fig. 2 is an elevation of th'e colloid mill;

Fig. 3 is an elevation showing the assembly of the colloid mill and thedriving motor;

Fig. 4 is a detail of the valve shown at 69 in Fig. 2; Y

Fig. 5 is a detail showing means for adjusting the stators;

Fig. 6 is a detail showing means for measuring the pressure in theworking gap; and

Fig. '1 is a flow sheet showing an arrangement of apparatus suitable forcarrying out the processes of the invention.

Referring to Fig. l, the casing Il is provided with a hopper I2, intowhich the yeast to be treated is fed, and an outlet port I3 for withfdrawing the treated yeast material. Shaft I4 is rotatably mounted incasing II by ball-bearings I5, I6 and Ithe corresponding bearinghousings I1, I8, and has mounted thereon the axially-spaced,frusto-conical rotors I9, and 2I. Encircling the rotors in closelyadjacent, non-contacting relationship are the stators 23, 24 and 25,which are adjustably mounted within casing II. The rotors and theircooperating stators define the respective working gaps 26, 21 and 28.

Bearing housing I1 is slidably mounted in the supporting member 29 whichis secured within the hopper I2 by the arms 3I. Bearing housing I8 isalso slidably mounted in casing II. The axial position of the shaft I4is adjusted by means of the wheel 32 which can be rotated, but isrestrained from axial movement by the tongues 33. Wheel 32 is threadedto the upper portion of bearing housing I1 so that by turning the wheelthe axial position of the housing l1, and therefore of the shaft I4, maybe changed,.thus changing the width of the working gaps 26, 21 and 28.The bearing housing I8, being adapted to slide in casing I I follows themovement of the upper housing without further adjustment. Feather keys34 and 35 prevent the corresponding housings from turning in theirsupports, and packing 36 is provided to prevent any uid yeast fromentering the ball-bearing I6.

Yeast is fed into the hopper I2 and passes over the inlet surface 31 ofrotor I9 to the working gap 26. Twosmall blades 38 are provided on shaftI4 to agitate the material and thoroughly mix it before it enters theworking gap.

Rotors I9, 20 and 2l are provided with the circumferential grooves 39and 40. Since all the rotors are similar, only the grooves on rotor I9will be referred to in detail. Groove 39 is connected to the inletsurface 31 by channel 42, and with groove 40 by the diametricallyopposite channel 43. Most of the material which iiows over surface 31enters the working gap 26, but a portion will enter channel 42 and flowdown to groove 39, where it will be distributed around the circumferenceof the rotor and mixed with the partially treated material which haspassed through the rst section of the working gap.

Most of the material then passes into the second section of the workinggap, but a portion will enter the channel 43 and flow into groove 40where it will again be distributed around the circumference of the rotorand mixed with' the material which has been treated in the secondportion of the gap. Finally, all the material passes into the lastsection of the working gap and undergoes further treatment.

Since the channels 42 and 43 are recessed in the surface of the rotor,the material can flow more readily through them than through the workinggap, so that there will always be sufiicient material to completely fillthe middle and last sections ofthe working gap despite the enlargingcross-section of the gap and the greater centrifugal forces acting onthe portions of the material near the outlet. Channels 42 and 43 areinclined somewhat backward to prevent too rapid a iow of material to thegrooves, and

placed at diametrically opposite points so as toV insure the mixing ofthe untreated material in channel 42 with the partially treated materialwhich comes through the first section of the working gap, beforeentering channel 43.

Casing II is provided with a water jacket 4,4, having inlet and outletports 45 and 46, respecltively, and a series of projecting ns 41 whichassist in cooling the material. In order to insure all the materialcoming in contact with the ns or the casing walls, there are 4providedbafiles 48, 49, 58, which radially project from the conical surfaces ofthe corresponding rotors at the outlet ends of their respective workinggaps. As the treated material leaves the working gap, it is diverted andthrown off by the baille onto the casing walls.l This insures thematerial coming in contact with as much of the cooling surface aspossible.

Casing II is also provided with a section 52 of material transparent toultra-violet radiation, such as quartz glass. The section is shaped toreceive the material as it is thrown oi baille 49 and expose it to theradiation from the mercury vapor lamp 53, as it flows down the surface54. The material is then confined in the narrow gap 55 between section52 and the inlet surface of rotor 2|, as it passes to the Working gap28. Due to the high rotor speed employed in the operation oftheapparatus the material in gap 55 is highly agitated, and thus allportions of the material are subjected to the direct action of theradiation from lamp 53 in a thin, highly agitated layer, therebyinsuring very efiicient irradiation. If desired, to prevent overheatingof the material, the section 52 may be air-cooled. Since the yeast hasundergone treatment in two working gaps before irradiation, much of thecell content has already been extracted. This assures efficientirradiation of the extract.

In order to permit adjusting stator 25 and still prevent leakage ofmaterial past the ends of the transparent section, the rubber gaskets 56and 51, and the threaded annular ring 58 and ring nut 59 are provided.When the desired adjustment of the stator has been made, ring 58 andring nut 59 are relatively rotated so that ring 58 bears down on section52 while ring nut 59 presses up on gasket 56. Thus a tight con` nectionbetween section 52 and casing II is assured. The individual statoradjustments permit adjustment of the working gaps so that each handlesthe material with the same rapidity. Thereafter, wheel 32 permitssimultaneous adjustment of the gaps according to the operat- "moredilute.

ing conditions and amount of treatment desired. The means fordetermining the width of the working gaps is indicated by numerals6I-64.

`The beam from an electric light 6| is directed through gap 26 and thetransmitted beam diverted through an opening in casing Il by thereflector 62. The reflected beam is magnified by a suitable lens system63 and impinges upon the ground glass plate 64, which may have gaugelines etched thereinv for determining the width of the beam. Furthermagnification can be employed if desired. In order to permit thetransmitted beam to pass the baille 48, a notch 68 is provided, the highspeed of the rotor making the light passing through this notch appearsteady to the observer. This permits ready determination of the width ofthe working gaps while the extractor is in operating condition. Byproperly adjusting the extractor, a uniform specifled amount oftreatment may be given to the yeast and large quantities of yeast may betreated rapidly and efficiently.

Casing is also provided with an opening 65 and a pressure reductionvalve 66 through which CO2, or other suitable non-deleterious gas may beintroduced into the extractor. The introduction of CO2 under a pressuregreater than atmospheric pressure, before the operation is begun, willremove any oxygen within the extractor and thereby prevent the formationof ozone during subsequent irradiation. If necessary, CO2,

may be introduced during the operation also.

Referring now to Fig. 2, pressure gauge 61 and vacuum gauge 68 areconnected to the valve 69. Pipe 10, communicating with the chamberbetween rotors |9 and 20, and pipe 1|, communicating with thechamberbetween rotors and 2|, are also connected to valve 69. The valve (Fig.4) comprises an outer casing 69 provided with four ports to whichthegauges and pipes,

are attached. Within rcasing 69 is a rotatable member 12 containing aright angle passageway, as shown. vBy turning member 12 either gauge 61,68, may be connected to either pipe 10, 1|, thus permitting the pressureconditions in both chambers to be conveniently determined. It has beenfound that sometimes, when the yeast is not suiciently dilute, thetreatment results in the material issuing from one of the working gapsin the form of a thick paste, rather than in the desired fluid form. Ifthis occurs, the

yeast cannot pass through the subsequent gap so a pressure will build upin the chamber and will be indicated by gauge 61. To correct thiscondition, the incoming yeast should be made If, on the other hand, arotor handles material faster than the preceding one, a vacuum may becreated int he intervening chamber and may be determined by gauge 61.Thermometer 13 is provided to indicate the ternperature of the treatedmaterial.

Fig.A 3 illustrates a suitable drive for the cen"- threaded portion ofstator 23. As the worm gear is turned the stator is caused to rotateabout its axis and, being threaded to casing Il, this results in anaxial movement of the stator and corre-` sponding adjustment of theworkinggap.

As shown in Fig. 6, a small passageway 80 may be provided inv stator 23,communicating with the working gap 2.6. When the machine is operatingthe pressure developed in the gap is communicated through passageway 80,and a connecting flexible tube 8|, to a suitable pressure trifugalextractor. The extractor II and a suitgauge (not shown). 'I'he pressurereading so obtained will give an indication of the iluidity of thematerial in the gap, and thus indirectly indicate whether or not thematerial has been mixture is passed through pipe 86,' which is pro'vided with a valve, into the colloid mill 81, the mill being driven by amotor 88. The colloid mill may .be of any suitable type, as, forexample, the one illustrated in Figs. 1 to 6.

A' suitablev source 89 of ultra-violet rays is positioned to irradiatethe yeast mixture. This is shown only diagrammatically, and may be theirradiating means shown in Fig. l. From the colloid mill the treatedmixture is passed through pipe 9| into tank 92. Cooling vcoils 93 areprovided in this tank for cooling the treated mixture. A suitable valveis provided at the outlet of the tank. The cooled yeast is withdrawnfrom tank 92 by the centrifugal pump 94 and Vdelivered under pressurethrough pipe 95 to the plate and frame lterpress 96. In the outlet pipeof the iilterpress is provided a twoway valve 91 so that the extract,may be delivered into pipe 98 for recirculation through the tank 92 andlterpress 96, or may be 4delivered directly into pipe 99 leading to tank|0|. Y

The extract is withdrawn from tank |0| by centrifugal pump |02 anddelivered under pressure to the filter press |03. This press may be ofthe type employing sintered glass, or wool, as a filter medium. Ifvdesired, any other suitable iilter medium may be employed which does notabsorb the vitamins from the extract.

From the second filter press |03 the extract is passed into tank |04,the outlet of which is provided with a valve, and thence into the vacuumpan |05. The vacuum pan is provided with a hot water jacket |06 forheating the extract for concentration. A suitable vacuum is maintainedin the vacuum pan by means of the vacuum pump |01.

From the foregoing description of my invention it will be appreciatedthat I have provided a marked improvement in the process of brewingbeer, and that this improvement is of considerable importance to thehealth of the beerconsuming public. It will also be appreciated thatalthough the process involving the preparation and utilization ofyeastcell extract has been developed primarily for the brewing industry,and is especially adapted therefor, the extract itself, because of itsagreeable flavor and vitamin potency, has other valuable uses. Thus theextract itself may be used as a tonic, or it may be added to potablesother than beer in order to increase their nutritional and healthgivingproperties. In such cases the brilliance and freedom from cloudiness ofthe extract may autolysis oi the yeast, and adding at least a. portionof the treated material to the beer.

2. In the process of brewing beer, the improvement which comprisestreating yeast in a colloid mill in the presence of salt and sugar toextract at least a portion oi the yeast-cell contents withoutsubstantial autolysis oi' the yeast, and adding at least a portion ofthe treated material to the beer.

3. In the process of brewing beer, the improvement which comprises aginga mixture containing yeast and a plasmolyzing agent, treating the agedmixture in a colloidmill to extract at least a portion of the yeast-cellcontents, the temperature and duration of the aging and of the colloidmill treatment being controlled so that substantial autoiysis of theyeast is avoided, and adding at least a portion of the treated materialto the beer.

4. In the process of brewing beer, the improvement which comprises agingat a low temperature a mixture containing yeast and a plasmolyzingagent, treating the aged mixture in a colloid mill without disruptionof. a substantial quantity of yeast cells, the temperature and durationof the aging and of the colloid mill treatment' being controlled sothata portion of the yeast cell content is extracted without substantialautoly- -substantially destroyed, treating the mixture after saidheating in a colloid mill without disruption of'a substantial quantityof yeast cells, the temperature and duration of the heating and of thecolloid mill treatment being controlled so that a portion of the yeastcell content is extracted without substantial autolysis of the yeast,and adding the extracted portion of the yeast cell content to the beer.

6. In the process of brewing beer, the improvement which comprisesheating a suspension containing yeast, salt and sugar to a degreesumcient to substantially destroy the fermenting power ofthe yeast,treating the mixture after said heating in a colloid mill withoutdisruption of a substantial quantity of yeast ce1ls,'the temperature andduration of the heating and of the colloid 05 mill treatment beingcontrolled so that a portion oi' the yeast cell content is extractedwithout substantial autolysis of the yeast, and adding the extractedportion of the yeast cell content to the beer. y

7. In the process of brewing beer, the improvement which comprisesheating a mixture containing yeast, a plasmolyzing agent and an aqueousmedium to a temperature not exceeding about C. and for a period notexceeding about 75 an hour to substantially destroy the fermenting powerof the yeast, the yeast being added to the aqueous medium while theaqueous medium is maintained at an elevated temperature' not exceedingabout 95 C., treating the mixture after said heating in a colloid millwithout disruption of a substantial quantity oi yeast cells, thetemperature and duration of the heating and of the colloid milltreatment being controlled so that a portion of the yeast cell contentis extracted without substantial autolysis o! the yeast, and adding theextracted portion of the yeast cell content to the beer. i

8. In the process of brewing beer, the improvement which comprisespreparing a mixture containing yeast and a plasmolyzing agent comprisinga sugar, treating said mixture in a colloid mill without disruption of asubstantial quantity of yeast cells. said preparing and the temperatureand duration of the colloid mill treatment being controlled so that aportion of the yeast cell content is extracted without substantialautolysis of the yeast, caramelizing the extract so obtained by heattreatment thereof, and subseguently adding the caramelized extract tothe eer.

9. In the process oi brewing beer, the improve- .ment which comprisesaging a mixture containing yeast and a sugar, treating the aged mixturein a colloid mill without disruption of a substantial quantity of yeastcells, the temperature and duration of the aging and the colloid milltreatment being controlled so that a portion of the yeast cell contentcontaining vitamins is extracted without substantial autoiysis of theyeast, removing the yeast cells from the extract so obtained, adjustingthe pH value of the yeast material during the course of the treatmentthereof to obtain a pH value of about 4.0-4.7 in the extract,caramelizing the extract having said pH value by heating in vacuo, thetemperature and length of heating being controlled so as not to destroythe vitamin potency of the extract, and subsequently adding the extractso prepared to the beer. i

10. In the process of brewing beer involving the preparation of avitamin yeast-cell extract by treating a yeast suspension in a colloidmill in the presence of a plasmolyzing agent and adding the extract tothe beer, in which preparation the yeast or yeast extract becomesheated, the improvement which comprises adjusting the natural pH of theyeast material with a nontoxic acid Prior to said heating to diminishthe deleterious eiIect of the heating on the vitamin potency.

ll. In the process of brewing beer involving the preparation of avitamin yeast-cell extract by aging a mixture of yeast, salt and sugarand treating the aged mixture in a colloid mill, and then incorporatingthe extract in the beer, in which preparation the yeast or yeast extractbecomes heated, the improvement which comprises adjusting the natural pHof the yeast material prior to said heating to a pH of about 4.0-4.7,whereby the deleterious eflect of the heating on the vitamin potency maybe diminished.

`12. In the process of brewing beer, the improvement which comprisesaging a quantity of yeast in the presence of salt and sugar at a lowtemperature, avoiding substantial autolysis, and destruction of theyeast cells, treating said mixture in a colloid mill in such a mannerthat a portion of the contents of the yeast cells is exing process:

sans@ y tracted without Adisruption of a substantial quantityfof cells,andv adding at least a portion of said mixture sov ftrea to the 'beerduring the'v brew- 13.- inthe 'process vf producing beef invoiving thepreparation of yeast-cell extract containing yeastvitamins `and theincorporation of the extract in the. beer,I lthe improvement whichcomprises preparing the yeast-cell extract for incorporation "in thefbeer by a process comprising treating yeast ina colloid mill in thepresence of salt` and sugarto 'extract a portion of the yeast-cellcontentwithout disruption of a substantial quantity of the yeast cells.

14. In the'process of producing beer involving 20. A process of`producing' a yeast-'cell extract y,which comprises aging a Vmixturecontaining the preparation of yeast-cell extract containing 1 yeastvitamins and the incorporation of the extract in the beer, theimprovement which comprises .preparing the yeast-cell extract forincorporation in the beer by a process comprising aging a mixture ofyeast, vsalt and sugar under such conditions of time and temperature asto avoid substantial autolysis of the yeast cells, and treating saidaged mixture in a colloid mill to extract a portion of the contents ofthe yeast cells without disruption of a substantial quantity of theyeast cells.

15. The process of preparing beer containing yeast vitamins whichcomprises adding yeast to beer wort, permitting fermentation to proceedto propagate the yeast and secure'an alcoholic content, separating yeastfrom the fermented wort, aging a mixture of the yeast and a relativelysmall quantity of salt and sugar under such conditions of time vandtemperature as to avoid substantial autolysis of the yeast cells,treating the aged mixture in a colloid mill vto extract contents of theyeast cells without disruption of a substantial quantity of yeast cells,separating the yeast cells from the extract, and incorporating theextract with beer after the second fermentation period thereof, wherebya finished beer con taining yeast vitamins may be obtained.

16. A beer containing yeast vitamins, but substantially free of yeastcells, having incorporated therein a yeast-cell extract substantiallyfree of products of autolysis and containing yeast vitamins, andprepared by the process comprising aging a mixture of yeast, salt andsugar under such conditions of time and temperature as to avoidsubstantial autolysis of the yeast cells, and treating the aged mixturein a colloid mill to extract a portion of the yeast cell content withoutdisruption of a substantial quantity of the cells.

17. A beer containing yeast vitamins, but substantially free of yeastcells, having incorporated therein a yeast-cell extract substantiallyfree of products of autolysis and containing'yeast vitamins prepared bythe process comprising admixing yeast and a plasmolyzing agent, treatingthe mixture in a colloid mill without disruption of a substantialquantity of yeast cells, the temperature and duration of the admixingstep and of the colloid mill treatment being controlled so that aportion of the yeast cell content is extracted without substantialautolysis of the yeast, thereby obtaining said yeast-cell extract.

18. A process ofproducing a yeast-cell extract which comprises treatingyeast in a colloid mill in the presence of salt'and sugar to extract atleast a portion of the yeast cell content.

19. A process of producing a yeast-cell extract which comprises aging ata low temperature a mixture containing yeast, sugar and a small quantityof salt, and treating the aged mixture 15 yeast andat` leastkoneplasmolyzing agent ofthe group consisting of` sugars, molasses, maltextract, g'um.arabicsodium chloride and potassium chloride, andtreatingv the aged mixturein a colloid'mill without disruption of asubstantial quantity of yeast cells, thetemperature and duration of theaging and of the colloid mill Vtreatment being controlled so that aportion of the yeast cell content is extracted without substantialautolysis ofthe yearst. Y

21. A vitamin product comprising a yeast-cell extract substantially freeof products of autolysis and obtained by the process comprisingadmixingl yeast and a plasmolyzing agent, and treating the mixture in acolloid mill without disruption of a substantial quantity of yeastcells, the temperature and duration of the admixing step and of thecolloid mill treatment being controlled so that a portion of the yeastcell content is extracted without substantial autolysis of the yeast.

22. A vitamin product comprising a yeast-cell extract substantially freeof products of autolysis and obtained by aging a mixture of yeast, saltand sugar, and treating the aged mixture in a colloid mill withoutdisruption of a substantial quantity of yeast cells, the temperature andduration of the aging and of the colloid mill treatment being controlledso that a portion of th-e yeast cell-content is extracted withoutsubstantial autolysis of the yeast.

23. In the process of brewing beer, the improvement which comprisesadmixing yeast and at least one plasmolyzing agent of the groupconsisting of sugars, molasses, malt extract, gum arabic, sodiumchloride and potassium chloride, treating the mixture in a colloid millin such a manner that a portion of the contents of the yeast cells isextracted without disruption of a substantial quantity of cells,substantial autolysis of the yeast during the course of treatmentthereof being avoided, and adding at least the extracted cell content tothe beer.

24. A process of producing a yeast-cell extract which comprises admixingthe yeast and a plasmolyzing agent therefor, and treating the mixture ina colloid mill in such a manner that av portion of the contents of theyeast cells is extracted without disruption of a substantial quantity ofcells, substantial autolysis of the yeast during the course of treatmentthereof being avoided.

25. A process of producing a yeast-cell extract which comprises heatinga suspension containing yeast and at least one plasmolyzing agentselected from the group consisting of sugars, molasses, malt extract,gum arabic, sodium chloride and potassium chloride to a degreesuiiicient to substantially destroy the fermenting power of the yeast,treating the mixture after said heating in a colloid mill withoutdisruption of a substantial quantity of yeast cells, the temperature andduration of the heating and of the colloid mill treatment beingcontrolled so that a portion of the yeast cell content is extractedwithout substantial autolysis of the yeast.

26. A process of producing a yeast-cell extract which comprisespreparing a mixture containing yeast and a plasmolyzing agent comprisingsugar, treating said mixture in a colloid mill without disruption of asubstantial quantity of yeast cells, said preparing and the temperatureand duration of the colloid mill treatment being controlled so that aportion of the yeast cell content is extracted without substantialautolysis of the yeast, removing the yeast cells from the extract soobtained, and thereafter caramelizing the extract by heat treatmentthereof.

27. A process of producing a yeast-cell extract which comprises aging amixture of yeast, salt and sugar under such conditions of time andtemperature as to avoid substantial autolysis-of the yeast-cells, andtreating said aged mixture in a colloid mill to extract a portion of thecontents of the yeast-cells without disruption of a substantial quantityof the yeast-cells.

28. A process of producing a yeast-cell extract which comprises heatinga suspension containing yeast, salt and sugar to a degree suiiicient tosubstantially destroy the fermenting power of the yeast, and treatingthe mixture after said heating in a colloid mill without disruption of asubstantial quantity of yeast cells, the temperature and duration of theheating and of the colloid mill treatment being controlled so that aportion of the yeast-cell content is extracted without substantialautolysis of the yeast.

29. vA process of producing a yeast-cell extract which comprises aging amixture containing yeast, and a sugar, treating the aged mixture in acolloid mill without disruption of a substantial Aquantity ofyeast-cells, the temperature and the extract, and caramelizing theextract having said pH value by heating in vacuo, the temperature andlength of heating being controlled so as not to destroy the vitaminpotency of the extract.

30. A process of producing a yeast-cell extract which comprises heatinga mixture containing yeast and a plasmolyzlng agent therefor to a degreesuch that the fermenting power of the yeast is substantially destroyedwithout substantial autolysis of the yeast, and treating the mixtureafter said heating in a colloid mill to extract at least a portion ofthe yeast-cell content.

31. A process of producing a yeast-cell extract which comprises heatinga mixture containing yeast and a plasmolyzing agent therefor to a degreesuch that the fermenting power of the yeast is substantially destroyed,and treating the mixture after said heating in a colloid mill withoutdisruption of a substantial quantity of yeast cells, the temperature andduration of the heating and of the colloid mill treatment beingcontrolled so that a portion of the yeast cell content is extractedwithout substantial autolysis of the yeast.

32. A process of producing a yeast-cell extract which comprises aging amixture of yeast with a plasmolyzing agent comprising sugar under suchconditions of time and temperature as to avoid substantial autolysis ofthe yeast cells, and treating said aged mixture in a colloid mill toextract at least a portion of the contents of the yeast cells withoutdisruption of a substantial quantity of the yeast cells.

33. A process of producing a yeast-cell extract which comprises aging amixture of yeast with a plasmolyzing agent comprising sodium chlorideunder such conditions of time and temperature as to avoid substantialautolysis of the yeast cells, and treating said aged mixture in acolloid mill to extract at least a portion of the contents of the yeastcells without disruption of a substantial quantity of the yeast cells.

ALBERT M. FISCHER.

